1. Field of Invention
This invention relates to an apparatus and method for the storage and displaying of operating parameters of a refrigeration system, and for controlling such system in response to the stored parameters. More particularly, the present invention relates to a method and apparatus for arranging the operating parameters of a refrigeration system within the cells of a plurality of data arrays whereby individual data array cells may be displayed and adjustments made to parameters stored therein.
2. Background Art
A large refrigeration system, such as that required for commercial refrigerators or air conditioners, generally has a large number of system operating parameters which must be adjusted and/or observed. Such a system typically comprises several air conditioning compressors, expansion coils and condensing coils. Various temperature controlled areas within the system generally have individual thermostats for controlling the temperature in their respective areas.
Operating parameters within the system may be categorized as either adjustable parameters or measurable parameters. Measurable parameters may, for example, comprise temperatures in various areas, compressor suction line pressure, and compressor operating time. Adjustable parameters may, for example, comprise compressor suction line cut-in and cut-out pressures, defrost cycle times, maximum and minimum levels of desired humidity within the building, and the like.
Control and display systems commonly used for refrigeration systems generally comprise a large control panel with a large number of gauges for reading measurable parameters, as well as control knobs, alphanumeric key pads and thumbwheel switches for setting the values of adjustable parameters. Control and display panels commonly used in the art frequently require a great deal of space, thus limiting the number of locations within a building where the control and display panel may be installed. Such control panels are also very difficult for the user to understand and to operate, and accordingly, require relatively highly trained personnel when adjustments to system settings are required. These prior art control panels suffer the added disadvantage that changes in the control system are not readily made, and often require modifications to the control panels to accommodate additional control functions.
It would be advantageous, therefore, to provide a small, compact control and display panel implemented with advanced display technology and microcomputers which could be installed at any convenient location within the building. Additionally, the flexibility of a control and display system driven by a programmable microcomputer would permit a single type of control and display system to be readily adapted to almost any refrigeration system. As refrigeration units are added to the system, simple changes in the stored program would permit the same control and display panel to be used without physical or structural modifications.
Typically, only a small number of the operating parameters of the refrigeration system must be displayed simultaneously for use by the system operator or the service technician. Alphanumeric display systems, such as liquid crystal display panels, provide a suitable means for displaying a limited amount of information. Under the control of a stored program microcomputer, a liquid crystal display provides sufficient flexibility so as to adequately display and label a small number of the system's operating parameters.
In some applications, such as the use of control panels in supermarkets, a number of control panels may be used to control various refrigeration systems. Also, multiple panels may be coupled to and controlled by the same computer. The computer may be placed in the building or at a remote location. The remote computer, thus, may be used to control the operation of control panels in more than one location or supermarket. Typically, a service technician visits the location where control panels are installed to make necessary repairs and/or to adjust the system parameters. Beepers and telephones are most commonly used as means for communication between the service technician and the remote control location for providing dispatching information, instructions to the technician to perform certain specified tasks or for reporting time spent and charges incurred by the technician on a particular job and the like. Such communication means can be time consuming and expensive. It would, therefore, be advantageous to provide an inexpensive and effective communication means between the control panel and the remote control locations for use by the service technician visiting a particular control panel.
The present invention provides an inexpensive and compact yet powerful and adaptable control and display unit requiring only a small number of operator actuated input devices and a single alphanumeric display for controlling a refrigeration system to permit display and adjustment of operating parameters within the system and for providing communication between the display unit and the remote control unit.